| 摘要 |
974,547. Reactor control rods. BABCOCK & WILCOX CO. April 4, 1963 [April 6, 1962], No. 13334/63. Heading G6C. A nuclear reactor control rod drive mechanism comprises a driving rod having a helical rack, a driven pinion for driving the rack, and means for preventing rotation of the drive rod when being driven. The invention may be used in conjunction with top or bottom mounted control rods. A reactor pressure vessel closure head 10 includes a number of control rod openings 11, above each of which is mounted a housing 12 between flanges 15, 16. Within and extending downwardly from each housing is a drive rod 22 having a coupling 24 at its lower end for engaging a control rod, and a helical rack 26 extending along a part of its upper portion. A square bore 3-0 passes axially through the drive rod and contains a square-section keeper 32, which is fixedly mounted in the top of the housing 12. Thus the drive rod is prevented from rotating. Driven shafts 18 drive pinions 28 in order to move the drive rods in and out of the reactor. In order to gain access to a control rod, all the control rods are fully inserted, and the top flange 15 and keeper rod 32 are removed. Rotation of the pinion 28 will now cause the drive rod to uncouple from the control rod, after which the entire housing 12, drive rod 22 and pinion 28 can be removed to give access to the control rod. If access is required to all the control rods, or some other part of the pressure vessel interior, after the drive rods have been uncoupled, the closure head 10 can be removed bodily with all the control rod drive assembly in place, with the exceptions of the top flanges and keeper rods. |
